Power amplifiers used in many wireless transmitters introduce non-linear distortion to the signal when operating near maximum output. Non-linearity is inherent to power amplifiers. In-band distortion changes the spectral components in the original signal frequency band, while out-of-band distortion causes expansion of the signal spectrum into adjacent channels causing interference with other users. Multicarrier communications, especially orthogonal frequency division multiplexed (OFDM) communications, are sensitive to non-linear distortion because of the high number of independently modulated and closely spaced subcarriers, which generally have a high peak-to-average power ratio (PAPR). To avoid in-band and out-of-band distortion, a power amplifier may be operated in a more-linear region; however this is extremely inefficient from a power consumption perspective making linear operation unsuitable for many battery-powered devices.
Thus there are general needs for systems and methods for power amplifier linearization that allow a power amplifier to operate efficiently while generating less in-band and out-of-band distortion.